1. Field of the Invention
The present invention relates to a video endoscopic apparatus for fluorescent diagnosis which picks up interior of a body cavity on the basis of auto-fluorescent light emitted from a living body to output image data used to diagnose whether the living body is normal or abnormal. The present disclosure relates to subject matter contained in Japanese Patent Application No. Hei10-122561 (filed on May 1, 1998), which is expressly incorporated herein by reference in its entirety.
2. Description of the Related Art
It is known that fluorescent light which is called xe2x80x9cauto-fluorescent lightxe2x80x9d is emitted from a living body when excitation light of a specific wavelength is irradiated upon the living body. Further, it is also known that since an abnormal part (tumor, cancer) of the living body is lower in intensity of auto-fluorescent light within wavelength band of green light than a normal part, the abnormal part is displayed darker than the normal part when it is formed into an image. There has been proposed a video endoscopic apparatus for fluorescent diagnosis which picks up the auto-fluorescent light emitted from the living body and displays an auto-fluorescent image of the living body available for diagnosing whether the living body is normal or abnormal, on the basis of such knowledge. One of those examples is disclosed in Japanese Patent Application Laid-Open No. 9-70384. In a video endoscopic apparatus for fluorescent diagnosis disclosed in the description, there is provided an image intensifier for amplifying the auto-fluorescent light between an objective optical system and an image sensor at the distal end of the video endoscope, taking it into consideration that the auto-fluorescent light is very weak. Therefore, according to this video endoscopic apparatus for fluorescent diagnosis, a bright auto-fluorescent image can be obtained because the auto-fluorescent image amplified by the image intensifier is picked up by an imaging device.
However, the outside diameter of the distal end of an insertion portion of the video endoscope must be large enough to contain the image intensifier. The distal end is inserted into the body cavity of a patient, so that there is a problem that a load of pain is imposed on the patient in case the distal end is too large. Also, since the image intensifier is comparatively expensive, there is a problem that the cost of the entire video endoscopic apparatus for fluorescent diagnosis will be increased if the image intensifier is installed at the distal end of the video endoscope.
It is an object of the present invention to provide a video endoscopic apparatus for fluorescent diagnosis capable of obtaining an appropriate image for fluorescent diagnosis even if any image intensifier is not used.
In the present invention, the following construction is adopted to achieve the above object.
A video endoscopic apparatus for fluorescent diagnosis in a first aspect of the present invention comprises a image pick-up device which picks up an auto-fluorescent image generated by irradiating excitation light onto a living body, a detection unit which detects a specific area where luminance value is within a predetermined range from the auto-fluorescent image picked up by the foregoing image pick-up device and a display control device which outputs an image signal indicating the specific area.
The apparatus being constructed in this way, the detection unit extracts the specific area from the auto-fluorescent image, and the display control device outputs an image signal indicating this specific area. Therefore, an image indicating shape and position of this specific area can be displayed on a display unit such as CRT or a liquid crystal display. Accordingly, if the range of luminance value covers that of the specific area is set to a range including the luminance value of auto-fluorescent light emitted from an abnormal part of the living body, the abnormal part is displayed as the specific area. For this reason, even if no image intensifier is provided, an appropriate image for fluorescent diagnosis can be supplied to a user (doctor or the like) of the video endoscopic apparatus for fluorescent diagnosis, so that the user can appropriately diagnose on the basis of the auto-fluorescent light. The detection unit and the display control device can be constructed, for example, as functions of a CPU (Central Processing Unit) executing a program or as an LSI, ASIC or the like.
A second aspect of the present invention is characterized in that the detection unit has a first extracting unit which extracts an area where luminance value is higher than a predetermined first threshold from the auto-fluorescent image and a second extracting unit which extracts, as the specific area, an area where luminance value is lower than a predetermined second threshold from the area extracted by the first extracting unit.
A third aspect of the present invention is characterized in that the image pick-up device has an illuminating device selectively emitting illuminating light in a visible band and excitation light in a ultraviolet band to irradiate a living body, and picks up a nomal color observation image of the foregoing living body irradiated with illuminating light in the visible band and an auto-fluorescent image of the living body irradiated with the excitation light respectively, and in that the detection unit extracts an area where luminance value is higher than the first threshold from the ordinary color observation image, extracts an area where luminance value is lower than the second threshold from the auto-fluorescent image, and detects, from area extracted from the nomal color observation image, an area included in the area extracted from the auto-fluorescent image as the specific area.
A fourth aspect of the present invention is characterized in that the display control device outputs an image signal for displaying a fluorescent observation image, in which only the specific area is indicated in a predetermined color. When constructed in this way, if there is an abnormal part in a living body as the object, the abnormal part is displayed in a predetermined color as a specific area in a fluoresecnt diagnosis image. For this reason, the user can easily diagnose whether or not it is an abnormal part.
A fifth aspect of the present invention is characterized in that the display control device outputs an image signal for displaying a fluorescent observation image, in which only the specific area is displayed in a predetermined color and the other area is displayed in color. The fluorescent observation image may be entirely displayed in monochrome. Also, the other area than the specific area within the fluorescent observation image may be displayed in pseudocolor. However, if only the specific area is displayed in a predetermined color and the other area than the specific area is displayed in color, the diagnosis will become more easier.
A sixth aspect of the present invention is characterized in that the pick-up device irradiates the living body with each illuminating light of red, green and blue in order, and at the same time, picks up images of the living body respectively irradiated with each illuminating light, and in that the display control device synthesizes the ordinary color image on the basis of images of the living body irradiated with the respective illuminating light, generates specific area image of the specific area extracted from the auto-fluorescent image and outputs image signal for displaying a fluorescent observation image comprising the specific area image superimposed on the ordinary color observation image.
A seventh aspect of the present invention is characterized in that the above-described display control device outputs image signal for displaying both of the ordinary color observation image and the fluorescent observation image at the same time. When constructed in this way, the user can easily diagnosis normality or abnormality of a living body because the user can observe two images while comparing them.
An eighth aspect of the present invention is characterized in that the display control device outputs an image signal for displaying the ordinary color observation image as a moving picture.
A ninth aspect of the present invention further comprises a switch, which is operated by an operator to generate a switching signal for causing the display control device to output an image signal for displaying only the ordinary color observation image or an image signal for displaying the ordinary color observation image and the fluorescent diagnosis image at the same time respectively.